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Radiator Fans not working - 1.8T AMB

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Radiator Fans not working - 1.8T AMB

Old 05-16-2019, 04:41 PM
1st Gear
Thread Starter
Join Date: May 2019
Location: Pasadena, CA
Posts: 2
Default Radiator Fans not working - 1.8T AMB

I've searched and read numerous threads and articles regarding this issue on my 2005 Audi A4 1.8T AMB, I've read through the Bentley to better understand and identify the location of critical components

Although most of the symptoms are similar to other posts, not every details applies to me. I've posted this question on a handful of Audi/W forums but have not had any satisfactory solutions. So I'm posting here in desperation. I'd like to make this work

Typical symptoms is car overheats when not moving. AC does not blow cold air when at a stand still.
What's different is that I can see the radiators fans begin to spin then shut down. This cycles over and over but never reaches full rotational speed and does not stay on. Behavior does not change when car reaches operational temp nor does it change when i turn on the AC.

Here's what I've done
1. The power control module and radiator fans were replaced by a local mechanic in 2017
2. I replaced the water pump/thermostat/J-Plug
3. I've replaced the lower Temp Sensor on the Radiator Outlet
4. I've replaced the upper Temp Sensor on the rear Coolant Flange
5. I've checked the two 40A and 50A fuses underneath drivers side dashboard (According to Bentley Manual) I do not have the fuses under the hood like other model years
6. #4 fuse is a 5A fan fuse and it is good.
7. Although this was replaced in 2017, I replaced the (J293) Fan control power module under the hood above the fans
8. I examined the 219 Relay underneath the ECU and it is clean. So I used contact cleaner and returned it back in place
9. I tested the radiator fan motors by connecting directly to 12V and the fans come on at full speed.
None of this has fixed the issue.

Using the VCDS here are my codes
3 Faults Found:
18010 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent
18080 - Coolant Fan Control 1
P1672 - 004 - Open or Short to Ground - Intermittent
18339 - Coolant Fan Control Module (J293)
P1931 - 002 - Malfunction - Intermittent
Readiness: 0010 0101

My assessment
18010 is because I've disconnected the battery every time I work on the car. But it could be a wiring fault. How would I test?
18080 is the 219 relay. (Item #8 above) I ordered a new one and it will be replaced today. But if its a wiring fault to one of the terminals, how would I isolate it?
18339 As stated above, (Item #7 above) I've purchased a new one (Expensive!)and installed it connected to the existing fans. It did not fix the problem. Fans still behave the same.

I'm now grasping in the dark. Someone suggested I replace the fans even though they are only two years old and they pass the 12V test when power is directly applied. I ordered new fans and I received them today. I will install them this weekend. But I'm not confident that this is going to fix the issue.
I've not received any sufficient answers from any of the other forums. Every suggestion thus far has been simply to replace this or that. I'm now reaching the point where I will have replaced every component in the fan circuit.

Anyone more knowledgeable with the VagCom please chime in.
Any recommendations or suggestions would be appreciated.
Old 05-28-2019, 02:13 PM
1st Gear
Thread Starter
Join Date: May 2019
Location: Pasadena, CA
Posts: 2
Default Solved

Someone in another forum suggested i replace the radiator fans. (Not a small feat - having to move the front bumper into "Service Position")
As i mentioned earlier I also got another brand new power module. Both items hit my wallet for about $500.00 USD

In doing so, I had to hard wire the two fan motors to the four leads off the power module. In doing this, it became apparent that the mechanic who replaced my fans and power module two years earlier had wired the fans in reverse polarity.

So after spinning my wheels replacing every component in the cooling system, everything now works as designed. Just in time for summer.

My big unanswered question is why I did not have heating or AC issues for the past two years. The fans could not have possibly worked at all wired incorrectly.

lesson learned.
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